(Indans (b) + Tetralins (c) +. Indens (d)). 23.6. 20.6. 6.5. 29.6. 11.5. 4. Cycloparaffins. 1-ring cycloparaffins. 2-ring cycloparaffins. 3-ring cycloparaffins. 39.7. 38.7.
Diesel Reforming for Solid Oxide Fuel Cell Application Di-Jia Liu, Shuh-Haw Sheen, & Michael Krumpelt SECA Core Technology Peer Review Workshop Tampa, FL January 27 - 28, 2005 Argonne National Laboratory A U.S. Department of Energy Laboratory Operated by The University of Chicago
The Critical Issues in Diesel Reforming Catalyst & Catalytic System Development Catalyst Cost -
•
Costly Rh usage Support Collapse
Efficiency & Selectivity Fuel property & chemistry
Catalyst Deactivation
Durability -
Metal vaporization & agglomeration Support stability Sulfur poisoning Coke formation
System
• •
C-deposit
Activity -
•
S poisoning Agglomerating S S S S
Fuel injection & mixing System integration
Reforming catalyst aging – an example 14
H2 yield (mol/mol-fuel)
•
Vaporizing
12 10 8 6 4 2 0 0
20
40
60
80
100
Time on stream (hr-1) 2 Pioneering Science and Technology
Argonne National Laboratory
Diesel Reforming Catalyst Development
3 Pioneering Science and Technology
Argonne National Laboratory
What Constitutes an Ideal Diesel Reforming Catalyst?
• • • • • •
Atomically dispersed active site. Stably anchored over the support surface. Effectively cleaving C-H, C-C & C=C bonds through oxidative process. Competitively releasing hydrogen over oxidation to H2O. Competitively oxidizing surface carbon over C=C bond growth. Minimum chemical binding energy with sulfur.
4 Pioneering Science and Technology
Argonne National Laboratory
Objective: Developing Perovskite Based ATR Catalyst •
The Perovskite Catalyst… - Low cost material. - Stable under high temperature & redox environment. - Exchangeable A & B sites lead to ionic dispersion & improve catalytic activity. ucture ABO 3 Str e it k s v Pero
CxHy
B A
CO, CO2 H2
H2O, O2
H2
e-
e-
Redox Cycle Conductivities of both e- and VO¨ of perovskite enhance catalytic active site through electron & oxygen vacancy transfers in a redox process. Pioneering Science and Technology
5
Argonne National Laboratory
Approach: ANL Perovskite Catalyst Materials
• • • •
Perovskites include chromite, aluminite, manganite, ferrite, … Self-combustion synthesis (Pechini method) B-site doped with Ru, Rh, etc… A-site exchanged with La, Sr, Ba, Gd, Ce, Pr, …
6 Pioneering Science and Technology
Argonne National Laboratory
Catalyst Activity Study: Test Apparatus & Conditions •
Fuel -
•
Temperature -
•
Reactor: 700 °C to 800 °C Preheating: 200 °C.
Input Mixture -
•
Alkane surrogate - C12H26 Organic sulfur - Dibenzothiophene (50 ppm S) Other HC surrogates – Monoaromatics, Polyaromatics, Cycloparffins …
ATR: O2/C = 0.3 ~0.5, H2O/C = 1 ~ 3
Space Velocity -
Fuel Flow Rate = 2.8~5.0x10-3 gfuel/gCat•sec GHSV = 50 K ~ 100 K hr-1
Diesel Reforming Catalyst Test Plant 7 Pioneering Science and Technology
Argonne National Laboratory
Catalyst Activity Study: Test Plant
8 Pioneering Science and Technology
Argonne National Laboratory
Catalyst Activity Study: Investigation on ATR Catalytic Light-Off for Perovskite Material 1.0 0.9
reforming
oxidation
Product Yield, mL/min
0.8
H2O
0.7
H2
0.6 0.5
O2
0.4 0.3
CO C4H10
0.2
CO2
0.1 0.0 100
200
300
400
500
600
700
800
Temperature ( o C)
Ru doped perovskites demonstrate low light-off temperature for hydrogen production suitable for SOFC application Pioneering Science and Technology
9 Argonne National Laboratory
Catalyst Activity Study: Basic Performance Parameters in Catalytic ATR Reforming Chemical Reactions in Diesel ATR Reforming: CnHm + xO2 + yH2O = nCO2 + (m/2 + 2n –2x)H2 + (y + 2x -2n)H2O An example:
C12H26 + 6O2 + 12H2O = 12CO2 + 25H2
Definition of Reforming Performance: H2 yield = CH2/ Cfuel Reforming efficiency = {CH2∆HcH2 + CCO∆HcCO}/ Cfuel∆Hcfuel COx selectivity = {CCO2 + CCO}/ nCfuel Ci = Molar flow of i, ∆Hci = Heat of combustion of i, n = Number of C in fuel molecule 10 Pioneering Science and Technology
Argonne National Laboratory
Catalyst Activity Study: Benchmarking New Perovskite Materials with Rh-Based Catalyst Performance of a selected group of perovskites 100
100%
80
80%
60
60%
40
40%
20
20%
i rN
r
Sr C
La
Sr C La
M
nR
u
u La
lR
La
A La
A Sr
Pr Fe R
u
u lR
u rR La
P
dC G
rC
rR
h rR
u
Sr C
La
La
C
rR
rR Sr C La Pioneering Science and Technology
u
0% u
0
COx Selectivity (%)
Reforming Efficiency (%)
benchmark
ATR input O2/C = 0.5 H2O/C = 2
11
Argonne National Laboratory
Sulfur Tolerance Study: Recoverable Activity over Perovskite Materials
S 4-MDBT S
Reforming Efficiency (%)
DBT
100
100%
80
80%
60
60%
40
40%
20
20%
COx Selectivity
Introducing 50 ppm sulfur in the form of DBT temporarily suppress reforming efficiency and COx selectivity.
Dibenzothiophene (DBT) and its derivatives are difficult to be removed from diesel through HDS process …
4,6-DMDBT S
0 0
50
100
150
200
250
300
350
0% 400
Time-online (min)
Catalyst re-activates after S is removed from fuel. 12 Pioneering Science and Technology
Argonne National Laboratory
Sulfur Tolerance Study: Resistance to Poisoning Improves at Higher Operating Temperature 100
T = 700 °C
b/f S-fuel
T = 800 °C
b/f S-fuel
a/f S-fuel
Reforming Efficiency (%)
80 w/ S-fuel a/f S-fuel
60
w/ S-fuel
40
20
0
Catalyst = LCR-800, O2/C = 0.5, H2O/C = 1.0, GHSV = 130,000 hr-1
Increase reaction temperature by 100 °C significantly improved catalytic performance in the presence of sulfur 13 Pioneering Science and Technology
Argonne National Laboratory
Sulfur Tolerance Study: Stable Reforming Observed during 100-Hr Aging Test with 50 ppm S in DBT 100%
80
80%
60
60%
40
40%
20
20%
0
0% 0
20
40
60
80
100
Time (hour) Reforming Efficiency (%)
COx Selectivity
120
T = 800 °C Fuel = 50 ppm S/C12H26 GHSV = 50,000 hr-1
Excellent catalytic stability was observed during 100 hour aging test with S contaminated fuel Pioneering Science and Technology
COx Selectivity
Reforming Efficiency (%)
100
14 Argonne National Laboratory
Coking Prevention Study: Issues with Heavy Hydrocarbon Components in Diesel Compound Type
Wt% Analysis, ANL
Wt% Analysis, Exxon
Ave. or Ref. Formula (ANL)
Paraffins
38.7
39.7
C16 H34
Cycloparaffins 1-ring cycloparaffins 2-ring cycloparaffins 3-ring cycloparaffins
29.6 11.5 4
23.6 20.6 6.5
C10 H21 C16 H32 C22 H38
7.3 3.2
3.2 0.9
C8 H8 C12 H16
Mono-aromatics Alkyl benzenes (a) Naphthenebenzenes (Indans (b) + Tetralins (c) + Indens (d)) Di-aromatics Alkylnaphthalenes (a) Acenaphthenes (b)/Biphenyls Acephthalenes (c)/Fluorenes (d)
Representative Molecular Structures
(c)
(a)
(b)
(d)
(a) 1.8 3.5 0.3
1.6 2.2 1.7
(b)
C13 H14 C9 H12 C13 H10
(c)
(d)
15 Pioneering Science and Technology
Argonne National Laboratory
Coking Prevention Study: Correlation b/w Efficiency & Residual HC’s Formation from Diesel Components 1
80
Unconverted HC (excld CH4)
0.1
60 0.01 40 0.001
20
e en
e
Fuel blends with Dodecane
5%
M
%
et hy
Bu
ln
ty
ap
lb
ht h
en z
al
en
lin tra Te % 10
ty Bu % 40
10
lc y
%
cl o
D
he
ec
xa
al in
ne
0
20
do de ca ne
0.0001
Reforming Efficiency (%)
100
Coking is affected by Temperature, O2/C, H2O/C, Catalyst & CATALYSIS CHEMISTRY of HYDROCARBONS. 16 Pioneering Science and Technology
Argonne National Laboratory
Coking Prevention Study: Deactivation Mechanism & Coke Formation by Polyaromatics •
•
Impact on ATR reforming by 1methylnaphthalene (1MN)
80
700 °C
800 °C
-
40
8
20
Residual HC's (%)
12
Efficiency (%)
60
16
Proposed Model of PAH impact on Reforming and C-formation Low cetane# / high Tig make them hard to oxidize. Competition b/w oxidation vs. C growth H2 CO CO2 H2O
HC’s
4
O2 Add 5% 1MN 0 0
100
200
300
400
0 500
Time (min)
1MN tentatively deactivates reforming. Activity recoverable after 1MN removal. Performance improves a higher T. O2/C & H2O/C have limited impact. Pioneering Science and Technology
Long resident time and slow decomposition of PAH over active site reduce reforming rate & increase residual HC’s & coke formation! 17 Argonne National Laboratory
Coking Prevention Study: Fishbone Analysis on Root Cause of Coking
ox i ca da t a tio ly n st ac s ti vi ty
High HC residues, C2, C3, C4…
Coking
Lo w
Su l fu
rp oi so ni ng
re tu ra pe m te s si ly ta ca O w H2 n Lo & atio O 2 tr w en of Lo nc n co tio s i ics po at m m co aro de vy a ow e Sl h al t e M
ss o l
Incomplete C-C bond breaking & oxidation
We are currently working on coking reduction through both catalyst & engineering improvements 18 Pioneering Science and Technology
Argonne National Laboratory
Catalyst Characterization: Identifying Perovskite Structure & Ru Active Site Conventional (XRD, SEM, ICP, TPR, BET…) and Advanced (EXAFS, XANES) characterization methods were used to study structure-activity relationship XRD confirms perovskite structure
EXAFS reveals Ru embedded in perovskite
LaSrCrRu 3 FT(χ(k)*k )
* Intensity (counts)
0.24
A B O
0.18
0.12
0.06
0
LaCrRu
1.5
3
4.5
6
R [Å]
10
30
50
2 th e ta Pioneering Science and Technology
N
R (Å)
σ2
LCSR1200
6.0
1.943
2.5x10-5
LCSR800
4.7
1.953
2.5x10-5
LCR800
4.3
1.962
1.0x10-5
70
19 Argonne National Laboratory
Summary: Knowledge Gained on Perovskite Catalyst & Its Applicability to SECA • • • •
Ru doped perovskites demonstrated excellent catalytic reforming activities comparing with Rh based catalysts. Active catalysts are the perovskites containing Ru at B site with oxygen vacancy and high surface area. Improved sulfur tolerance and perovskite stability were demonstrated through 100-hr aging at higher operating temperature. Root cause of catalyst deactivation through coking by aromatics was identified. Improvement through catalyst material refinement and new reactor engineering approach is underway.
Perovskite ATR catalysts provide new low-cost alternatives in fuel reforming for SECA. 20 Pioneering Science and Technology
Argonne National Laboratory
Diesel Fuel Mixing & Cool Flame Study
21 Pioneering Science and Technology
Argonne National Laboratory
Critical Issues in Fuel Mixing Diesel Air
• • •
Recyc. Exhaust
Completed vaporized fuel is essential for catalytic reforming. Diesel fuel cannot be evaporated without fractioning. Incomplete mixing creates “hot spots” on the catalyst and leads to sintering & coke formation.
reformate 22 Pioneering Science and Technology
Argonne National Laboratory
ANL Approach: Diesel Injection Technology Improvement & Pre-reforming through Cool Flame •
Diesel Injection – A joint effort between ANL and International Truck and Engine Corporation (ITEC) - ANL is currently building a test facility for air-steam-fuel-exhaust gas mixing study with catalyst testing capability for ANL autothermal reforming process. - ITEC provides diesel-fuel injectors and fuel-injection control system
•
Cool Flame – An alternative method to further improve fuel mixing and pre-reforming. - What is cool flame? - How it may benefit SECA fuel reforming effort? - Our approach – Investigating operating condition and gas composition in cool flame.
L. Hartmann, K. Lucka, and H. Kohne, 2003 23
Pioneering Science and Technology
Argonne National Laboratory
Diesel Mixing Study: Fuel-Air-Steam Mixing Facility Under Construction High Pressure Engine Oil Accumulator Oil Filter
H Water Reservior
Pressure Multiplier Injector Control Module
LP N2 Tank
Pressure Regulator
Diesel Fuel
T
HP N2 Tank Fuel Filter
Valve
Fuel Heater
Fuel Injector
Valve Humidity Sensor Temperature Sensor Pressure Sensor
Pre-heated Air Compressed Air
Mixing Chamber PTH
Sapphire Window
6”-4” Reducer Diagnostic Chamber
Purge N2 P T H Data
Data
PC
Cooling Air
Solenoid Valve Valve Control Pulse Trigger P T H Control
Exhaust Gas Outlet (to outdoor) Blower Disposal Tank
Mist Trap
Exhaust Gas from Hood 24
Pioneering Science and Technology
Argonne National Laboratory
Diesel Mixing Study: ITEC Diesel Fuel Injector
• Pulsed injection with pulse rate of 10 ~ 70 Hz (500 ~ 4000 rpm for 4-cylinder engine) • Injection duration Below 1 ms at idle to 20 ms at high load • Injection nozzles 6 holes around • Fuel injection rate Peak : Idle :
105 mm3/stroke at 240 bar and 600 rpm 9.2 mm3/stroke at 45 bar and 600 rpm 25
Pioneering Science and Technology
Argonne National Laboratory
Diesel Mixing Study: Demonstration of Fuel Injection Test Chamber
26 Pioneering Science and Technology
Argonne National Laboratory
Acknowledgements •
This work was supported by the U.S. Department of Energy, Office of Fossil Energy – Solid State Energy Conversion Alliance (Program Coordinator - Wayne Surdoval, Program Manager - Norman Holcombe) and Office of Energy Efficiency and Renewable Energy – FreedomCAR & Vehicle Technologies (Program Manager - Sid Diamond).
•
Thanks to the technical support by - Cécile Rossignol - Mike Schwartz - Hual-Te Chien - Jameel Shihadeh - Martin Bettge - Jeremy Kropf 27 Pioneering Science and Technology
Argonne National Laboratory